Echo
by snowhalo
Summary: It was never a hallucination bothering Sam after Castiel broke the wall inside his head. Spins off the canon after Repo Man and goes to somewhere entirely else. Spins off the canon after Repo Man (7x15) and goes to somewhere entirely else. Spoilers up until that point along with one detail revealed in First Born (9x11).
1. Prelude

It's hard to be a hallucination. Lucifer could see now why the Winchesters had been so reluctant to do their part in the apocalypse. To exist only in the back of someone's mind, pushed away and suppressed, trying to desperately cling to the mere existence was straining. And hope that maybe, just maybe, one day you could break free and take control, to force your captor down and reverse the game. It had been boring and long, for the most part. Of course he had had the privilege to see and know things that only Sam had seen. It was a small plus side to the whole ordeal.

When Castiel had come to steal Sam away from him, Lucifer had grabbed tight onto Sam, any part of Sam, and refused to let go. He had succeeded, in a way. He had been able to keep Sam's soul, if not all of him. After all, the soul was what was most of Sam. The part that he could have fun with, play with endlessly as years went by. But he hadn't been allowed even that for a very long time as soon Death had descended into the Pit and taken Sam's soul with him. Lucifer hadn't wanted that to happen. Sam had been the only thing in there to keep him entertained as Michael had been a douche and kept his distance to Lucifer, his vessel neatly tucked under his arm. So Lucifer had fought back, wrapped around the mutilated thing that was Sam's soul and hold it close with all of his might. It hadn't been enough; Death had taken Sam and Lucifer had felt almost hollow, like a part of him was missing.

It turned out that had been literal. Lucifer wasn't new to the fact that every time an angel leaves a vessel, part of that angel's grace sticks with the body. But what he didn't know was that when an angel held onto a human soul as desperately as he had, he would not only leave his claim onto that soul, but also willingly give more of his grace to it. Whether the soul wanted it or not.

So even when Lucifer was left alone with his mood-swingy older brother, part of him hid itself inside the deepest cuts of Sam's soul, holding onto the familiar warmth. Death, of course, saw exactly what had happened, had even anticipated it. And so he put up the wall inside Sam's mind, forcefully separating those little pieces of Lucifer from both his soul and body, and never told the truth about it to anyone.

And until Castiel broke that wall between Lucifer infested parts and the rest of Sam, no one was the wiser. But when that first crack hit the wall, when Sam fell limply on the ground, Lucifer was struck with a familiar feeling of _Sam_. Tiny little cracks had appeared in front of him, inviting him in, allowing him to seep just a bit through to the other side. It was only enough for him to see Sam, feel his body and soul. But it was enough.

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><p><em>NA: This is just a Prelude, the actual First Chapter will be the second and is where the story actually begins. I'm hoping to publish new chapters as often as possible and not have more than two weeks tops between chapters. Let's hope I can keep it up._

_This story will be mostly unbetaed. I'll proof read every chapter, but english not being my native language, I apologize if there's mistakes. Please feel free to point them out to me if you find them. :)_


	2. Chapter 1 - The cold in all of us

Sam was exhausted. Lucifer had been keeping him up for four days in a row now and no matter what he did, no matter how hard he pushed that old scar in his hand, the hallucination wouldn't go away. In the end he had even taken out Ruby's old knife and pressed it on his arm, almost making himself bleed to death. But the Satan had stayed exactly where he was, casually commenting his actions and suggesting him that if he would pull the knife from his wrist to elbow, he would get better results. Heaven really was a nice place to be, Lucifer had told him when he had slipped into a blessed unconsciousness while Dean had been frantically trying to patch him up before he would be forced to take a tour in upstairs with the Devil.

But the unconsciousness hadn't lasted more than a few hours and Sam had woken up to Lucifer acting like he was selling something in an auction. It sounded vaguely like his objects were different parts of Sam's body and the cherry on the top, his soul. Sam never found out if he had actually been sold, as Dean decided to take that moment to barge in the room, only so he could yell at Sam about doing something so stupid as to nearly kill himself. Most of Dean's rage ended up mixing with Lucifer's raised voice, but Sam got the gist and promised he would never do anything like that again.

After his shouting and one rare brotherly hug that told Sam a lot about Dean's current state, he left the motel room with a command to get some sleep. Sam knew it was a lost cause, but closed his eyes anyway and for a few seconds had a complete silence. And then Lucifer jumped on the bed next to him and leaned on the headboard, stretching out his legs and shooting a content smile at him.

"Remember when we were still in the Cage," he started like he was reminiscing something with fondness beyond words, "all those long nights we spent together. Oh, how you screamed. You sound so pretty when you scream, Sammy. Maybe you could give me a one little scream and I would let you sleep for a while?" he suggested slyly, sliding his hand on Sam's upper arm and stroking softly like he were his pet. Sam responded by shrugging the hand off and turning onto his side, closing his eyes tightly and trying to think about something else, anything else. Lucifer let out an amused huff and started singing Van Halen's _Running with the Devil_ loudly and off-key. After a moment he rose up and added a beat to his song by jumping on the bed.

"Come on, Sam, this silent treatment is getting old. If you would just work with me here, we could have so much fun," Lucifer whined and plopped back onto the bed. He leaned against Sam's back and cocked his head to see the hunter better. Sam was still pretending he didn't exist. It had been a huge mistake to acknowledge Lucifer in the first place. Talking to him had been stupid and now he was paying for it. Sam didn't want to think what might happen if he would continue on that path. Nothing good, surely. Lucifer let out a dramatic sigh and leaned his arms onto Sam's side. "See, this is what I don't get. You are willing to talk to me, but only when the other option is your brother getting killed. It's like you're trying to force me to kill him," he mused, watching his own feet in apparent interest and wiggling them from side to side. Sam tensed noticeably, but stayed quiet. The next time Lucifer spoke, it was with a smile that sounded clearly in his voice.

"Let's make a deal, shall we, Sammy? You will be a good little boy and provide me some entertainment, and I don't have to create it myself. What do you say?" Sam stayed silent. Lucifer shrugged nonchalantly. "Suit yourself." Lucifer petted Sam's hip and started whistling while the room started filling with thick black smoke slowly and maniacal cackling filled Sam's ears.

Sam gave up the hopes of sleeping quickly. Lucifer didn't seem any more likely to let him sleep than before, and lying on the bed as a useless lump didn't suit him well. When Sam rose up with effort, Lucifer stopped playing the violin he had been occupied with for some time now and pointed the bow at him.

"You don't look so good, Sammy. You sure you want to get up yet? Who knows what will happen if you go running around like that." From anybody else the words might have been caring. From the Devil, they just sounded mocking with a touch of amusement. Sam figured he would be more than enthusiastic to see "what would happen" if Sam were to "go running around" somewhere. So he stayed put and opened his laptop instead, picking up the research for the latest leviathan activity. Lucifer came to hover behind his shoulder, leaning closer than was necessary and breathing to the side of his neck. Sam shuddered reflexively and leaned away from the breath. Lucifer chuckled.

"You cannot escape from me. It would be more beneficial to embrace what you've got," he told Sam smoothly, moving closer so he could continue breathing on the exposed skin. Sam kept leaning farther and farther away until he was almost off the chair, annoyance written clearly on his face.

"Stop it!" Sam finally snapped, jumping off the chair and walking backwards until there were several feet between the two. Lucifer straightened up and Sam would have sworn he saw a slight smile and a look of wonder on Lucifer's face, but when he blinked and looked again, all that was left was a blank mask of indifference with a slight curve of impending smirk on the corner of Lucifer's lips. Lucifer cocked his head just a tad to the side and regarded Sam with curiosity in his eyes, like he was watching an animal developing a new and fascinating trait. To Sam it seemed mocking, reminding him of small kids who were purposefully annoying their peers with things like "not touching you" and simply staring each other creepily to make the other nervous. It was working, Sam had to admit. Lucifer was making him extremely nervous by stopping on his tracks and focusing on him way too hard. It made Sam's insides feel cold and at the same time stuffy, like something was pushing against him from the inside. Sam shivered and turned away.

Lucifer was alarmingly quiet after that. It was like he had learned something new and needed some alone time to determine what to do with that information. It unnerved Sam greatly and made him want to break the silence against his better judgment. In the end Sam had had enough and simply walked out of the room and to the cool night air, only to be accompanied by the still silent Lucifer wading after him deep in thought. The angel didn't seem to want to leave him alone even if he was in his own thoughts. The idea that maybe this was some new way of trying to get his attention crossed Sam's mind and he decided to try and pretend that his hallucinatory companion wasn't even there. But the cold feeling still persisting inside of him wouldn't budge and kept reminding him that something was wrong.

Sam ended up making a short, silent walk around the motel and nearby park, finding his brother sitting on a park bench and drinking beer, his eyes directed towards the sky with a wistful look. Without a word, Sam sat down next to him and followed his gaze up to the stars. They were quiet for a long time, just watching, until Dean finally got back to himself and sighed deeply.

"What do you think happens to angels when they die?" he asked softly, the slight slur to his voice telling Sam the beer in Dean's hand wasn't the first drink of the night. Sam shook his head.

"I don't know. Maybe they just… seize to exist?" he questioned. Lucifer didn't offer any kind of opinion or fact to the guess and when Sam looked around, he had disappeared. Sam frowned. Lucifer hadn't left him alone for one second since he had gotten back to the previous motel room after saving Dean from the serial killer and his beloved demon. Turning his body Sam focused on finding the hiding angel from somewhere, but the hallucination stayed away. There was a weird tug somewhere in Sam's stomach and he slumped back onto the bench, leaving his search to that. If Lucifer was going to leave him alone for time being, Sam would be happy to take advantage of it. Dean hadn't answered to him and as he was still staring at the sky, Sam was fairly sure he hadn't even noticed Sam's odd behaviour. His eyelids were heavy and his posture was too limp for public area. Sam sighed.

"We should go back to the motel. This town seems like a dead end, no point of staying here longer than necessary. Let's get some sleep and hit the road early, huh, Dean?" Sam said and went to pat his brother on the back but as his hand connected with Dean, it felt like he had just clapped it on to a burning ember. Sam yelped and pulled his hand away as quickly as possible, automatically turning his palm up to see the damage that kind of heat always brought with it. There was nothing. His hand looked perfectly normal and the pain subsided as quickly as it had appeared. Dean had jumped up at his yelp and was now standing next to the bench, scanning the nearby area for danger, a knife in his hand and ready for battle despite his less than ideal state; he was swaying on his feet and looked about ready to pass out. The reason for the sudden burn didn't stay unknown for long.

"Oh no Sammy, if you won't allow me to touch you, you won't get to touch either," came a voice from behind him and when Sam turned, he found Lucifer leaning against a tree and looking like nothing had happened during the past hour. The curiosity and quiet consideration were gone and there was nothing to suggest they had ever been there. Sam grimaced but didn't say a word. Instead he rose up from the bench and glanced at Dean, who was watching him warily after determining there was no immediate danger and that Sam's sudden terror was hallucination induced. He looked worried. Sam shook his head at his brother and jerked it once towards the motel. Both boys turned and started making their way back to their room, the Satan whistling happily as he followed in their wake.

The next day Sam woke up to someone playing with his hair. After determining quickly that he hadn't in fact gotten laid yesterday and then forgotten about it, he came to the only possible conclusion. It was soon proved correct as Sam turned to look behind him, only finding Lucifer inspecting his locks with concentration and care. Sam stared. It wasn't unusual for him to wake up with the hallucination occupying the other side of his bed, but he had certainly never done anything like this. Usually when the Devil decided to harass Sam this early in the morning, it was in some obnoxious and over pronounced way. Now he just lay there, fingering Sam's hair like it was something precious and otherworldly.

The second thing hitting Sam was the fact that he had just woken up. Lucifer had let him sleep. Sam had been sure Lucifer was going to keep him up until he would go insane and end up in a mental facility or just simply dead, but right now he felt like he had had a good night's sleep. He still felt fatigued, but not nearly as much as the day before. He didn't feel like he was going to fall over or pass out spontaneously. Sam was so shocked from all of this that he didn't even remember to shrug Lucifer off and get far enough from him that there wouldn't be any chances of physical contact.

Lucifer looked up after a while of stunned silence and gave Sam an unreadable smile. It felt ominous, but then ominous was what Lucifer did, so it shouldn't have had come as a surprise. Sam wanted to ask. He wanted to know why he was suddenly allowed to sleep and why on Earth was Lucifer checking out his hair. He wanted to ask, but he knew it was stupid. He had already acknowledged Lucifer twice, and both times had ended up to something bad or inexplicably weird.

Lucifer didn't wait for the question long, instead letting out a huge sigh and turning to pick up something from the bedside table. When he turned back, he dropped a small paper back book onto Sam's stomach.

"I read a book," he informed Sam matter-of-factly, managing to look expectant, innocent and downright devilish at the same time. Sam gulped and picked up the book, propping himself up to sit against the headboard.

It was a trashy romance novel, that much was clear from the pink cover sporting a cliché, muscled man with a long and luscious dark hair, holding a blonde adoring girl close to his bare chest. Sam grimaced and was about to raise an eyebrow at Lucifer to demonstrate his horrible taste in books, when his brain registered a detail in the picture and he did a double take. The topless man in the picture had a tattoo on his chest, a tattoo that was more than familiar to Sam. The same tattoo was inked into his own chest with black ink to prevent demons from possessing him. Sam swallowed and let his eyes travel over the book more carefully than before, ignoring the snicker sounding from the man next to him.

The book was called _Soulbound._ That in itself raised some alarms inside Sam, and when his eyes travelled down to read the author's name, he couldn't stifle the despairing groan rumbling out of his chest. _Carver Edlund_, told the book cover to Sam. Resisting the urge to throw the book at the nearest wall and proceed with shooting the thing several times before dousing it with gasoline and setting it on fire, Sam started inspecting the girl in the cover. His first guess was that the girl was a depiction of Jessica. With her long, blonde hair and sparkling blue eyes she might as well be. But the girl had straight hair instead of curly, and so Sam was forced to think of Ruby in her first vessel. However, neither of the two girls seemed to really fit to the drawn picture; it was something in-between, something darker, and in a way that made Sam uncomfortable, so much more beautiful. Not wanting to think about that further, Sam flipped the book to see what the back cover had to say.

"_When Sam meets Lucille Belial, he thinks she's just another witness to a weird murder. But as the investigation goes on, it becomes clear that something is not quite right about the girl. Sam decides to investigate her further only to find out Lucille isn't as ordinary as he had first thought. And the more Sam finds out about her, the deeper he falls into a pit of emotion. Will Sam let the mysterious girl seduce him to abandon everything he knows and take the biggest risk he has ever taken before?"_

Sam wasn't sure he had read the blurb right. It couldn't be right. The idea of Chuck writing trashy novels about him was beyond absurd, even if he had to consider the possibility that Becky might have had something to do with that. Sam flipped the book open to see the publishing date only to find out it had been published before he and Dean had met Chuck. Sam ended up convincing himself that Chuck had had gotten a bit too drunk one night and decided to do something different with his characters for a change. He wasn't sure if that made him feel any less disgusted and if he should go punch the writer in the face regardless.

"It's a rather good read, considering. I do think he could have made me a bit less slutty and desperate, but all in all, very entertaining," Lucifer commented from next to his ear and Sam jumped at the sudden sound. He had forgotten the hallucination was still there, watching his every move and smirking at his horrified expression. Lucifer's words didn't help the situation in the slightest.

"_You_?!" he exclaimed, throwing the book away like it had suddenly turned into something poisonous. It hit the corner of a table and fell on the floor with a quiet thud. Lucifer gave him a pitying look.

"Lucille Belial? I am disappointed in you, Sam, it just couldn't be any more obvious," he berated Sam and shook his head sorrowfully. Sam had to admit he was right. The name all but screamed Lucifer and Sam was ready to bet it was intentional. But why in all heavens would Chuck write a trashy book about him and the Devil? It wasn't like something like that would or had happened – far from it, Sam considered anything even close to it impossibility. Unlike Lucifer, he noted, who seemed extremely pleased that such a book existed.

"Maybe I should have found myself a female vessel… Would that make you more, ah, consenting?" Lucifer asked with a glint in his eyes, and suddenly the book was back in his hands again and he flipped it open, lowering his eyes on the words and started reading;

"_Sam had never seen anything more beautiful than the woman lying beneath him, writhing under his touch, her blue eyes shut tightly against the pleasure. He knew it was wrong, he knew it would only lead to one destination, but he couldn't help himself. His heart was full of love and unadulterated lust and that alone drove him forwards and made all his doubts disappear._

'_Ahhhh, Sam!'_" Lucifer took time to drag out the keen, pulling Sam out of his horrified stupor all at once. His face contorted in disgust and he went for the book with sudden aggressiveness. But Lucifer had anticipated it, moving the book farther away from Sam and so the hunter ended up lying on top of Lucifer, hands trying to grab the book that right now was the reason of his brain cells dying. Lucifer let out a laugh and smirked. "_Ohhhh, Sam, take me, I want you, I need you!_" he mimicked, abandoning the book onto the bed and wrapping his arms around Sam, pulling him closer against him. Sam squirmed, but Lucifer was far stronger than he would ever hope to be. Lucifer snaked his hand into Sam's hair pulling him down so he could whisper into his ear. "You know you want to," he breathed seductively, and then let his hands fall off of him with a devious chuckle. Sam scrambled up as quickly as he could. Swearing as he ended up on top of the book that was the sole reason he had ended up into Lucifer's clutch, he grabbed the offending object and threw it viciously to the other side of the room where it hit the wall with a loud thump and landed on the floor a moment later. Dean stirred on the other bed at the noise and surfaced with bleary eyes and confused expression.

"What the hell is going on?" he asked upon seeing the seething Sam sitting on the dishevelled bed, his hair all over the place like someone had just attacked him. Sam was still staring at the book like he was trying to set it on fire with sheer willpower. Dean followed his gaze and his confusion grew.

When his brother didn't offer any explanation for the aggressively hateful stare, Dean got up with a groan and went to pick up the book. It was snatched out of his hand before he could see more than a glance of the long haired man and the blonde in his arms. Sam had been hoping it had been just another hallucination. Dean had proved that wrong by seeing the book in the first place. He didn't need to make it more of a reality by finding out what it was about and making Sam's life hell because of it. Lucifer snickered in the background and Sam was certain he knew what Sam was thinking. Sam let out a silent growl.

"Get dressed. We have a prophet to kill."

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><p><strong>AN:** The story behind the name: Lucille, next to being platantly similar to Lucifer, also means Light (Lucifer = Bringer of Light, in latin). Belial is one of the many names for demon/devil.


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